Process for producing a quick-cooking product of rice or other starchy vegetable



United States Patent PRUCESS FOR PRODUCING A QUICK-COOKING PRODUCT OFRICE OR OTHER STARCHY VEGE- TABLE Kenneth K. Keneaster, Houston, Tex.,and Harrison E. Newlin, Prairie Village, Kaus., assignors to ConvertedRice, Inc., Houston, Tex., a corporation of Delaware No Drawing.Application September 20, 1954, Serial No. 457,312

11 Claims. (Cl. 99-80) Our invention relates to a method of producing aquick-cooking product of rice or other starchy vegetable. Thisapplication is a continuation-in-part of application Serial No. 279,244,filed March 28, 1952.

An object of our invention is to provide a new and improved process forproducing a quick-cooking rice product having the followingcharacteristics:

(1) The finished product before re-cooking resembles whole-grain ricewith well-rounded and substantially unbroken kernels of a good, clear,white color;

(2) The product can be re-cooked in five minutes or less by using asimple and conventional cooking procedure.

(3) When re-cooked and presented at the table, the product resembleswhole-grain rice of good quality with the individual grains large,distinct, and very well-rounded and of an even, light, and flufiytexture.

(4) The re-cooked rice has the appearance and flavor of rice which hasnot been treated by our process.

Another object of our invention is to provide a new and improved processwhich is not limited to rice but may be applied to other starchyvegetables.

Another object of our invention is to provide a new and improved processfor producing a quick-cooking product having good keeping qualities.

Another object of our invention is to provide a new and improved processwhich requires no new or special equipment but which can be carried outby the utilization of equipment now readily available.

Another object of our invention is to provide a new and improved processwhich is simple and inexpensive and equally adapted for treating largeand small quantities of a given vegetable.

Other objects and advantages will become apparent as the descriptionproceeds.

In general our novel process comprehends the following steps:

(1) Steeping in water to a point approaching saturation; (2) Cooking inwater;

(3) Separating the vegetable from the cooking water; (4) Cooling;

(5) Freezing;

(6) Thawing;

While the process is applicable generally to starchy vegetables, such ascereals, potatoes, peas, beans, macaroni, spaghetti, etc., we shall forpurposes of illustration describe a specific example in which ourprocess was utilized to prepare a quick-cooking rice.

A batch of whole-grain or head rice was first steeped to a pointapproaching saturation by holding the rice under Water for a period ofsixteen hours, with the water temperature at about 80 F. The rice usedin this example had previously been treated by the process described inUnited States Patent No. 2,358,251 and had a moisture content of from10% to 12% by Weight at the start of the steeping step.

2,813,796 Patented Nov. 19, 1957 After steeping, the rice was cooked inwater, with one gallon of water being used for each pound of rice. Themixture of water and rice was first warmed to a temperature of C. duringa period of twenty minutes and then cooked at a gentle boil for a periodof thirty-six minutes with the temperature of the cooking water varyingfrom 96 C. to 101 C. and being predominantly between 98 C. and 99 C. Thecooking was stopped abruptly to avoid overcooking and uneven cooking,the cooking Water being drained from the rice over a period of 1%minutes. The rice was then divided into quantities not exceeding a poundeach, and each of these quantities placed in a sealed jar. The sealedjars were then put in ordinary mechanical refrigerators having atemperature of approximately 37 F., care being taken that only a fewjars were placed in each refrigerator, so that the cooling capacities ofthe household refrigerators used were not overloaded. The sealed jars ofrice were left in the refrigerators until cooled to about 37 F.

The jars were removed from the refrigerators, wrapped in insulatingmaterial, and placed in a freezing unit having a temperature of l8 C.The freezing unit used was of the so-called deep-freeze type commonlyused in homes and stores. The insulation about the jars delayed the lossof heat so that it took approximately one hour to cool the rice tofreezing temperature, another two hours to freeze it, and another hourto reduce the temperature of the rice to approximately 18 below zerocentigrade. At the end of the four hours, the jars were removed from thefreezing unit and the rice permitted to thaw at room temperature. Duringthis thawing opera tion, the covers were kept on the jars to preventevaporation of moisture or drying of the rice during the thawingoperation, but the Wrapping around the jars was removed to facilitatethawing. The rice was then removed from the jars, spread out, and driedin a strong current of dry, hot air, Whose temperature was not permittedto exceed F. The drying was continued until the rice had a moisturecontent of less than 6%, and this drying operation was completed inapproximately six hours.

At the conclusion of the drying operation the kernels were well-rounded,substantially unbroken, and had a good, clear, white color. The kernelsresembled ordinary cooked white rice which had not been treated eitherby our process or the process of said Patent No. 2,358,251. A part ofthis batch was then re-cooked by placing a cupful in three cups of waterand bringing to a boil on an ordinary stove. As soon as the water cameto a boil, the excess water was drained off and the rice was ready foreating. This re-cooking required less than five minutes, and produced aproduct in which the individual grains were large, distinct, and verywell rounded, and had an even, light, and fluffy texture. In color,flavor, and all other respects, this product resembled ordinary whiterice of good quality.

Some of the kernels produced by our process in this example were notimmediately re-cooked but were kept in containers at room temperaturefor a period of four months. Upon inspection at the end of this period,the kernels showed no deterioration and when re-cooked in the mannerpreviously described, gave the same results as those kernels which werere-cooked shortly after the completion of the drying operation.

Several specific examples are given herein of steeping times andtemperatures which may be employed to give good results. It will beunderstood that various other steeping times and various othertemperatures may be employed, the steeping time varying inversely withthe temperature. The important consideration in this respect is that thetemperature of the steeping water should be maintained below the pointwhere gelatinization of the starch of the vegetable being steepedoccurs, and for the particular temperature chosen the steeping periodshould be long enough so that the'vegeta'ble is "completely wettedthroughout. This does not necessarily mean that that the vegetableiscompletely saturated and cannot take up more water, but the completewetting through to the center generally occurs as the vegetable isapproaching saturation. In most cases, and particularly with rice, thevegetable is satisfactorily steeped when it has been wetted through toits center, and this can'be determined by visual inspection of a grainof rice which has been broken apart transversely. In other specificapplications of the process, the rice was steeped respectively, for aperiod of four hours in water at a temperature of about 120 F.; for aperiod of three-quarters hour at 140 F.; and for one and one-half hoursat 120 F., and in each case satisfactory results were obtained. It willbe understood, of course, that the steeping time and temperature of thesteeping water will vary to some extent according to the nature of therice employed as a starting material and also according to the initialmoisture content of the rice, which may vary between 9 and percent. Thesteeping period can also be shortened by applying pressure, but thepressure applied should not be great enough to disrupt the cells, andfor rice should not exceed approximately 100 pounds p. s. i. Thesteeping operation can also be facilitated by initially subjecting therice or other vegetable to a vacuum to remove air therefrom before thecommencement of the steeping operation.

In the cooking step it is important that the rice or other vegetable beneither overcooked nor undercooked. If the vegetable is overcooked incarrying out our process, it will be too soft when placed upon thetable, and if undercooked in carrying out our process, it will notrecook as rapidly as desired. The cooking time will vary with thetemperature, as indicated by the following chart:

Generally speaking, our experience has shown that in preparing rice thecooking time should be accurate within approximately one minute when ahigh temperature is used, and within approximately fifteen minutes whena low temperature is used. The proper cooking time depends to someextent upon the percentage of moisture which the rice will absorbwithout swelling to the point at which it becomes ragged. We have foundthat ordinary dried white milled rice must be cooked for a shorter timethan rice which has been treated by the process described in the UnitedStates Patent No. 2,358,251, as it stands less swelling before becomingragged. A relatively smooth surface is desired on the cooked riceparticles in order to avoid diminishing the yield of the process as aresult of abrasion and fracture of the particles caused by a raggedsurface during the subsequent process mg.

In the specific example given above, we described the rice as beingcooled by placing it in sealed jars in a refrigerator. The same resultcan be accomplished by pouring the rice into cold water which may thenbe drained for several minutes and under conditions which avoid dryingthe rice during draining. This latter method of cooling is particularlyapplicable where large quantities are to be cooled, although therefrigerator method may also be used for large quantities provided thenecessary refrigerating capacity is available. The method of cooling isnot critical and other methods can be utilized, but care should be takento avoid drying during the oooling operation.

In the freezing step, it is important that the actual'freezing'ta'kesplace over a'rel'atively long period of time and thatthe vegetable is not supercooled prior to the transition to the frozenstate. In other words, a cooling curve in which temperature is plottedagainst time in the freezer would show an initial relatively steep slopefollowed by a nearly fiat stretch or plateau during actual change to afrozen state, and when all of the vegetable has been frozen, thetemperature again drops rapidly, finally reaching that of the freezer.For rice, the freezing plateau should cover at least an hour, and betterresults were had when this plateau extended over a period of threehours.

In the preceding example, we wrapped the containers with insulatingmaterial to slow down the rate of heat transfer in the freezer. The sameresult was accomplished in another performance of our process byutilizing a freezer having a low ultimate temperature of 20 C. or evencolder, but with a small heat transfer capacity in comparison with thesize of the rice batch. In this case it was not necessary to useinsulating material, but in this and all other cases the vegetable mustbe covered to avoid drying during the freezing step. Excellent resultsare obtained when the rice to be frozen is placed in aluminum trays, forexample, of a size about 24" x 12" X A", and covered with aluminum foilcrimped to the edges of the tray to effectively seal the rice againstthe loss of moisture during the freezing step. It will be understoodthat other types of containers may be used for the rice during thefreezing step, but that for purposes of economy the containers shouldpreferably be designed so that rapid heat transfer between rice and theambient freezing medium can be attained.

During the slow transition to the frozen state, large ice crystals areformed which break down the continuous colloidal starchy structure andproduce a porous kernel which readily absorbs water during there-cooking step. We have found that the water in the rice freezes atbetween 31 and 32 F., and that the desired result is not obtained wherethe rice is reduced to a lower temperature than this before freezingtakes place. Experience indicates that such supercooling is avoided byquickly reducing the temperature of the rice down to this freezingtemperature in the initial part of the freezing operation. Thereafter,as previously pointed out, the rice remains at its freezing temperaturewhile it is slowly transformed to the frozen state, whereupon a furtherquick drop in temperature takes place. It is not necessary that thislatter drop in temperature be carried to any predetermined point, but itshould be sufficient to insure complete freezing of all of the moisturein the vegetable. If desired, the vegetable may be retained almostindefinitely in the frozen state, but for most purposes, it is moredesirable to have the thawing step immediately follow the freezing step.

The thawing operation is not critical if carried out at room temperatureor in warm air over a period of several hours, generally five or more.In the case of rice, it is important to prevent drying during thisthawing operation in order to prevent the individual grains fromsticking together, and to obtain the desired characteristics andappearance in the final product, but with vegetables which have notendency to stick together, there is no reason why drying should not bepermitted during this thawing operation. The drying operation must becarried out at such a rate as to prevent spoilage, and for rice thisrate is such that the total drying time should not exceed 8 hours. Thetemperature of the drying air must be kept below the point at whichdestruction of the quality of the rice will occur. The temperature atwhich this will occur depends to a large extent on the conditions underwhich the thawing operation has been conducted, and where the thawinghas been conducted at room temperature over a period of several hours,drying in warm air of about F. should continue for a period of not lessthan about 3 /2 hours for rice, as otherwise the kernel will becomechecked and therefore less attractive. Different considerations applywhere accelerated thawing and drying is done, and it has been found thatin order to avoid vitrified rice particles in the final product, it isnecessary to carefully control the temperature and humidity conditionsduring thawing, especially when subsequent accelerated drying isaccomplished by air at temperatures ranging up to 250 F.

Further specific examples of the application of the process to starchyvegetables are set forth below:

Commercially dried White milled rice was steeped for two hours in waterat 120 F., after which time the steeping water was raised to boilingtemperature and the rice allowed to cook in the boiling water forminutes. The moisture content of the rice at this time was in theneighborhood of 70%, this being below the point at which a raggedsurface would be caused to appear. The rice was then discharged from thecooking vessel and quickly drenched in cool water in order to preventfurther self-cooking. After the rice was drained of excess water, it wasplaced in aluminum trays in layers of about /8" depth, and then coveredwith an aluminum foil which was crimped to the sides of the tray toprovide a substantially moisture-proof container for the rice. The trayswere then placed in a freezing compartment in which the ambienttemperature was maintained at about minus 12 C. The rice was allowed toremain in the freezing compartment until the temperature of the riceitself had dropped to about 32 F. and had remained at this temperaturesteadily for about 3 hours. At the end of this time, the temperature ofthe rice dropped off, indicating that freezing in the temperatureplateau had been completed. The block of frozen rice was then removedfrom the tray and placed upon a steel mesh belt which carried it througha thawing zone in which air at about 85 F. was directed through therice. The thawing by the forced blast of air was continued for about 30minutes, after which the thawed rice was placed on a belt which carriedit through a drying chamber in which air initially at a temperature ofabout 230 F. was directed on it for about 2 hours. The drying operationreduced the moisture in the rice to about 8 percent and the finishedproduct resembled whole grain rice with well-rounded and unbrokenkernels of a good, clear, white color. A portion of the product wasplaced with water in a cooking vessel and the water brought to a boil inabout 5 minutes. The rice was then removed, ready for consumption. Thecooked rice had the appearance and flavor of properly cooked whitemilled rice with no trace of a starchy or chalky taste frequently foundin quick-cooking rice products. The other portion of the product wasstored for a period of time in its dried condition and then cooked forconsumption as described above. Its characteristics of taste, flavor andform were equally favorable, with the individual grains being large,distinct, well-rounded and of a uniform light and fluffy texture.

A common commercial variety of dried navy beans was steeped in water at180 F. for about 3 hours, at the end of which time it was found byvisual inspection that a representative sample of the beans had beenwetted through to their centers. The steeping water was then raised to aboil, and the beans were boiled for about one hour. Thereafter the beanswere discharged from the cooking vessel and drained of excess water.They were then placed in shallow aluminum trays and covered withaluminum foil crimped to the sides of the trays to provide asubstantially moisture-proof container. The trays were then placed in afreezing compartment in which the ambient temperature was maintained atminus 15 C. The temperature of the beans was observed by remoteindicators, and it was found that after the temperature of the beans haddropped to about 32 F. and had remained at this temperature for about 4hours, a further drop, to below the freezing temperature occurred,

indicating that the freezing, for purposes of this process, had beencompleted. The block of frozen beans was then removed from the tray andthawed by a blast of air at about 90 F. After the beans were thawed,they were subjected to a blast of drying air maintained at about 180 F.until moisture content of the beans dropped to about 6%.

It was found that the beans processed in this manner could be cookedinto a palatable state in about 10 minutes, as compared with the cookingof 3 to 4 hours generally required for commercial dried beans.

A commercial variety of sea-shell macaroni was steeped in water at atemperature of about F. for 2 hours, after which the steeping water washeated to a boil. The macaroni was allowed to cook in the boiling waterfor 15 minutes, after which it was removed and drained of excess water.The macaroni was then placed in fiat aluminum trays and covered withaluminum foil, which was crimped to the sides of the trays to preventmoisture loss during the freezing operation. The macaroni was placed ina freezing compartment in which the ambient temperature was maintainedat about minus 18 C. After a period of cooling, the macaroni dropped toa temperature of about 32 F., and remained at this temperature forapproximately 3 hours. At the end of this time, a further temperaturedrop was observed, indicating that the freezing operation had beencompleted. The block of frozen macaroni was then removed from thefreezing compartment and subjected to thawing by a stream of air atabout F. for approximately 20 minutes. The macaroni was thereaftersubjected to drying air at a temperature of about 200 F. until themoisture content had been reduced to that of the starting materialmacaroni. The form and appearance of the processed macaroni product wassubstantially identical to the original. It was found that the cookingtime of the processed macaroni, in boiling water, was about 5 to 7minutes as compared to 15 to 18 minutes required for satisfactorilycooking a starting material macaroni.

In a modified form of our process, the steeping step can be eliminatedand the rice or other vegetable cooked without any preliminary steeping.Under such circumstances the cooking step must be continued from 10% to25% longer than where a preliminary steeping is used, the variation inthe longer cooking time being due somewhat to the variations in themoisture content of the rice or other vegetable prior to cooking. In allother respects, this modified form of our process may be the same asthat previously described. The quality of the product produced by thismodified form of our process is not as high as that resulting from thepreferred form, but is sufficiently good to suffice for many purposes.

It is to be understood that our invention is not limited to the detailsdescribed but may assume various other forms and includes allmodifications, variations, and equivalents coming within the scope ofthe appended claims.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is:

1. That process of treating rice and other starchy vegetables to producea quick-cooking product which can be quickly re-cooked to correspond intaste and appearance to ordinary cooked vegetables, comprising steepingthe vegetable under water for a period of several hours until thevegetable is approximately saturated with water, cooking the vegetableunder water, abruptly terminating the cooking by separating thevegetable from the cooking water, cooling the vegetable under non-dryingconditions, freezing the vegetable by producing a rapid temperature dropto the freezing temperature of about 3132 F., maintaining said freezingtemperature for a period of at least an hour and thereafter producing asecond rapid temperature drop, thawing the vegetable under non-dryingconditions, and drying the vegetable without changing its appearance orflavor.

2. That process of treating rice to produce a quickcooking whole grainproduct which comprises steeping the rice under water for a period ofseveral hours until the rice is approximately saturated with water,cooking the rice under water, abruptly terminating the cooking byseparating the rice from the cooking water, cooling the rice undernon-drying conditions, freezing the rice by producing a rapidtemperature drop to the freezing temperature of about 3132F.,maintaining said freezing temperature for a period of at least an hourand thereafter producing a second rapid temperature drop, thawing therice under non-drying conditions, and drying the rice at a temperatureless than 110 F. until the moisture content is approximately six percent by weight.

3. That process of treating rice and other starchy vegetables to producea quick-cooking product having the appearance of a vegetable cooked inthe ordinary way, said process comprising the steps of completelycooking the vegetable under water, abruptly terminating the cooking byseparating the vegetable from the cooking water,

cooling the vegetable under non-drying conditions, freez-' ing thevegetable by producing a rapid temperature drop to the freezingtemperature of about 31-32 F., maintaining said freezing temperature fora period of at least an hour and thereafter producing a second rapidtemperature drop, thawing the vegetable under non-drying conditions, anddrying the vegetable in warm air.

4. That process of treating rice to produce a quickcooking whole grainproduct comprising completely cooking the rice under water, separatingthe rice from the cooking water, cooling the rice to a point severaldegrees above freezing under non-drying conditions, rapidly reducing thetemperature of the rice to the temperature of about 3l-32 F. at whichthe moisture in the rice will freeze, maintaining such freezingtemperature for at least an hour until all of the moisture in the ricehas been converted into large ice crystals, rapidly reducing thetemperature of the frozen rice several degrees below its freezingtemperature, thawing the rice under non-drying conditions, and dryingthe rice under conditions which will eliminate cracking and spoiling ofthe rice kernels.

5. That process of treating starchy vegetables to produce aquick-cooking product having its original shape and flavor comprisingcompletely cooking the vegetable in water, separating the vegetable fromthe cooking'water, cooling the vegetable, rapidly dropping thetemperature of the cooled vegetable to the temperature of about 31-32 F.at which the moisture therein will freeze, maintaining the vegetable atsuch freezing temperature for a period of time of at least an hoursufficient to permit the formation of large ice crystals therein,thawing the vegetable, and drying the vegetable.

6. That process of treating rice and other starchy vegetables to producea quick-cooking product comprising completely cooking the vegetable inwater, separating the vegetable from the cooking water, cooling thevegetable, rapidly dropping the temperature of the cooled vegetable tothe temperature of about 31-32 F. at which the moisture therein willfreeze, maintaining the vegetable at such freezing temperature for aperiod of time of at least an 'hour suflicient to permit the formationof large ice crystals therein, thawing the vegetable, and drying thevegetable to a less than normal moisture content.

7. That process of treating rice to produce a quickcooking whole grainproduct comprising completely cooking the rice in water, separating therice from the cooking water, cooling, the rice, rapidly dropping thetemperature of the cooled rice to approximately thirty-one and onehalfdegrees Fahrenheit, maintaining the vegetable at such freezingtemperature for a period of time of at least an hour sutficient topermit the formation of large ice crystals therein, thawing thevegetable, and drying the vegetable to a less than normal moisturecontent.

8. That process of treating rice to produce a quickcooking productcomprising completely cooking the rice, cooling the rice to a pointseveral degrees above freezing under non-drying conditions, rapidlyreducing the temperature of the rice to the temperature of about 31-32F. at which the moisture in the rice will freeze, maintaining suchfreezing temperature for at least an hour until all of the moisture inthe rice has been converted into large ice crystals, rapidly reducingthe temperature of the frozen rice several degrees below its freezingtemperature, thawing the rice under non-drying conditions, and dryingthe rice under conditions which will eliminate cracking and spoiling ofthe rice kernels.

9. In a process for preparing a quick-cooking, wholegrain rice productwherein the rice is saturated with water, precooked, slowly frozen,thawed and dehydrated, the steps of accomplishing the freezing bymaintaining the rice, without super-cooling, at the maximum constanttemperature at which the water within the rice will freeze for a periodof at least one hour and until the said water is frozen, and retardingof the loss of water content of the rice during freezing.

10. In a process for preparing a quick-cooking, wholegrain rice productwherein the rice is saturated with water, precooked, slowly frozen,thawed and dehydrated, the steps of accomplishing the freezing bymaintaining the rice, without super-cooling, at the maximum constanttemperature at which the water within the rice will freeze for a periodof about three hours and until the said water is frozen, and retardingof the loss of water content of the rice during freezing.

11. In a process for preparing a quick-cooking wholegrain rice productwherein the rice is saturated with water, precooked, slowly frozen,thawed and dehydrated, the steps of accomplishing the freezing byplacing the rice in a substantially sealed container to retard loss ofmoisture content of the rice during freezing, and maintaining the rice,without super-cooling, at the maximum constant temperature at which thewater within the rice will freeze for a period of at least one hour anduntil the said water is frozen.

References Cited in the file of this patent UNITED STATES PATENTS2,021,721 Gibbon Nov. 19, 1935 2,278,472 Musher Apr. 7, 1942 2,358,251Huzenlaub Sept. 12, 1944 2,438,939 Ozai-Durrani Apr. 6, 1948

1.THAT PROCESS OF TREATING RICE AND OTHER STARCHY VEGETABLES TO PRODUCEA QUICK-COOKING PRODUCT WHICH CAN BE QUICKLY RE-COOKED TO CORRESPOND INTASTE AND APPEARANCE TO ORDINARY COOKED VEGETABLES, COMPRISING STEEPINGTHE VEGETABLE UNDER WATER FOR A PERIOD OF SEVERAL HOURS UNTIL THEVEGTABLES IS APPROZIMATELY SATURATED WITH WATER, COOKING THE VEGETABLEUNDER WATER, ABRUPTLY TERMINATING THE COOKING BY SEPARATING THEVEGETABLE FROM THE COOKING WATER, COOLING THE VEGETABLE UNDER NON-DRYINGCONDITIONS, FREEZING THE VEGETABLE BY PRODUCING A RAPID TEMPERATURE DROPTO THE FREEZING TEMPERATURE OF ABOUT 31*-32*F., MAINTAINING SAIDFREEZING TEMPERATURE FOR A PERIOD OF AT LEAST AN HOUR AND THEREAFTERPRODUCING A SECOND RAPID TEMPERATURE DROP, THAWING THE VEGETABLE UNDERNON-DRYING CONDITIONS, AND DRYING THE VEGETABLES WITHOUT CHANGING ITSAPPEARANCE OR FLAVOR.